MVVM in Java with ViewModel + LiveData

Instructions

Use Jetpack ViewModel as the state holder and LiveData as the observable transport between ViewModel and Fragment/Activity. The view is dumb: it renders an immutable UI state and forwards events.

1. Immutable UI State

Model UI state as a single immutable record (Java 17). One state per screen — not one LiveData per field.

public record ArticleListUiState(
        boolean loading,
        List<Article> articles,
        String errorMessage
) {
    public static ArticleListUiState initial() {
        return new ArticleListUiState(false, List.of(), null);
    }